At a college fair on Wednesday at the Le Méridien hotel here, 20 American universities made their pitches to aspiring students, many of whom had long hoped to study in the United States. But as the students checked out presentations from colleges ranging from the State University of New York at Binghamton to Abilene Christian University in Texas, several expressed concerns about going to America under a Donald J. Trump administration.

“It’s the main topic of conversation among my friends,” said Palak Gera, 21, who is applying to graduate programs in pharmaceutical science in North Carolina, Illinois and North Dakota. “They don’t want to apply to the U.S. under Trump.”

Aman Kumar, 18, who is looking at universities in California, said, “In his campaign, he’s discriminating against Muslim and other brown and black people,” adding, “I’m thinking of applying to Canada.”

This year, the number of international students in United States colleges surpassed one million for the first time, bringing more than $32 billion a year into the economy and infusions of money to financially struggling colleges.

College admissions officials in the United States caution that it is too early to draw firm conclusions about overseas applications, because deadlines for applications are generally in January and February. But they are worried that Mr. Trump’s election as president could portend a drop in international candidates.

Canadian universities have already detected a postelection surge in interest from overseas.

“We have seen an increase in applications from the U.S. and from international students in the last week,” Jocelyne Younan, the director of global undergraduate recruitment at McGill University in Montreal, wrote in an email. “We’ve also seen an increase in students inquiring about McGill on social media.”

Traffic on a University of Toronto website for international applicants surged the day after the election, officials there said — and most of it came from Americans. “Visits to our recruitment website from the U.S. are typically around 1,000 a day,” said Ted Sargent, the university’s vice president, international. “On Nov. 9, that spiked to 10,000.”

On the same day, there was an increase in visitors from Britain and India, Mr. Sargent said. “Our positive message as a university, but also as a city and a country, definitely is about openness to people from around the world and a real inclusiveness,” he said.

A disruption in the flow of international students could be particularly worrisome for universities that balance their books with income from international students, who generally pay higher tuition.

“We have already received inquiries from prospective students who are in the applicant pool,” Mr. Naidu said. “They’re asking, ‘Is it safe for me to come there?’

At Indiana State University, 1,000 of the 13,500 students are foreign, including many Saudis who transferred this year from Idaho State, and officials are concerned, said Santhana Naidu, an associate vice president for communications and marketing.

“We have already received inquiries from prospective students who are in the applicant pool,” Mr. Naidu said. “They’re asking, ‘Is it safe for me to come there?’ and generally getting the lay of the land.” Mr. Naidu will be among officials meeting this week at the university, in Terre Haute, to determine what they can do to assuage fears.

Scott Manning, the director of global programs at Susquehanna University, a liberal arts college in Selinsgrove, Pa., said he had heard before the election that two prospective students from China were waiting until after the vote to submit visa documents necessary to attend Susquehanna.

“They were kind of spooked about threats Trump made about the South China Sea, back and forth with Japan about some uninhabited islands, and trade issues in general,” Mr. Manning said. The students, who were considering an English-language program beginning in January as a precursor to fall enrollment, have still not submitted their documents, he said.

Officials at Ohio State University said it was too early to tell whether the election result would affect international applications, adding that there had been an increase so far this year, although most were received before Election Day.